Virtual channel platform

ABSTRACT

A virtual channel platform is disclosed. Said virtual channel platform comprises two spaced electrode plates, which can provide an electric field, and a voltage source electrically connected to the two electrode plates. Said plates define a virtual reservoir and a virtual channel. When the voltage source provides a voltage between the electrode plates, the electric field generates a force to drive a driven fluid streaming from the virtual reservoir to the virtual channel, allowing the virtual channel to be filled with the driven fluid fully.

RELATED U.S. APPLICATION DATA

This Application is being filed as a Continuation-in-part of U.S. patentapplication Ser. No. 12/385,771, filed on Apr. 20, 2009, currentlypending.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The instant disclosure relates generally to a platform for fluidicmanipulations, more particularly, to a platform to controllably pumpfluids in an electric-field-formed virtual channel without physicalchannel walls. Even more particularly, the instant disclosure relates toa platform for fluid pumping and fluid formation by dielectrophoresis.

2. Description of Related Art

Pumping liquids in microchannels is essential to the study ofmicrofluidics and practical to the wide applications includinglab-on-a-chip (LOC) and micro total analysis systems (μTAS).

Various microfabrication techniques have been developed to carve andseal microchannels on silicon, glass, or polymer substrates. To driveliquids in microchannels, different pumping mechanisms have beeninvestigated. For example, mechanical micropumps transport liquidsthrough hydraulic pressure differences, while non-mechanicalelectroosmotic pumping relies on the zeta potential on the channel walland electric potential difference across the liquid in a microchannel.

Although the microfabricated physical channel walls assist pumping in amechanical or/and electrical way(s) as described above, they eliminatethe controllability of the liquid streams during operation for differentapplications. In addition, the fabrication and sealing of themicrochannels are usually complicated. The problems of liquid leakageand dead volume are commonly observed.

Please refer to FIGS. 4A and 4B, which show a conventional dropletmanipulation platform 1 a. The droplet manipulation platform 1 a has twoelectrode plates 11 a. One of the electrode plates 11 a has a pluralityof discrete electrodes 111 a so as to define a fluidic space 2 a betweenplates. The fluidic space 2 a is only used for the passing through of adroplet 3 a by utilizing the discrete electrodes 111 a. However, inpractice, the droplet manipulation platform 1 a has some limitations,such as liquid in the droplet manipulation platform 1 a cannot beapplied to capillary electrophoresis or light guidance which is usuallyperformed along a continuous liquid channel complicatedly carved andsealed on silicon, glass, or polymer substrate.

Hence, the inventors of the instant disclosure believe that theshortcomings described above are able to be improved and finally suggestthe instant disclosure which is of a reasonable design and is aneffective improvement based on deep research and thought.

SUMMARY OF THE INVENTION

An object of the instant disclosure is to provide a virtual channelplatform which has no substantial flow channel and drives fluidsurrounded by immiscible filling fluid(s) based on an electric field.With no substantial flow channels, the platform is easily manufactured.

Another object of the instant disclosure is to provide a virtual channelplatform flexibly controlling and delivering fluids without substantialflow channels and moving components (valves or pumps).

To achieve the above-mentioned objects, a virtual channel platform inaccordance with the instant disclosure is provided. The virtual channelplatform includes a first and a second electrode plates spaced forforming an electric field, with the first electrode plate having a firstsubstrate and a conductive layer disposed on the first substrate, withthe second electrode plate having a second substrate and a patternedconductive electrode disposed on the second substrate. While theconductive layer and the patterned conductive electrode define a virtualreservoir and a virtual channel in communication with the virtualreservoir; a voltage source electrically connected to the conductivelayer and the patterned conductive electrode; and a main driven fluidand a surrounding fluid arranged between the first and the secondelectrode plates, with the surrounding fluid being immiscible with themain driven fluid, and the main driven fluid is arranged in the virtualreservoir. When the voltage source provides a voltage between theconductive layer and the patterned conductive electrode, the electricfield generates a force to drive the main driven fluid streaming fromthe virtual reservoir to the virtual channel, so as to fill the virtualchannel with the main driven fluid.

Advantageously, the operating frequency of the voltage is greater thanthe cutoff frequency of the virtual channel platform.

Advantageously, the electric field established by the two electrodeplates generates a dielectrophoretic force in order to drive the maindriven fluid of a higher dielectric constant along the strong electricfield into the region of lower permittivity, i.e., the surroundingfluid, in the planar passageway.

Consequently, the virtual channel platform of the instant disclosure hasthe merits as follows: the virtual channel platform of the instantdisclosure has a simple structure and has no moving component, and thevirtual channel platform may be manufactured via a simple lithographyprocess without complex channel structures and packaging; furthermore,the virtual channel platform of the instant disclosure can drive themain driven fluid by voltage applications at different frequencies toachieve programmable operation and control.

Additionally, the virtual channel platform of the instant disclosuredoes not need an enclosed substantial flow channel, and doesn't need amoving component (valve or pump) to drive the main driven fluid.

To further understand features and technical contents of the instantdisclosure, please refer to the following detailed description anddrawings related the instant disclosure. However, the drawings are onlyto be used as references and explanations, not to limit the instantdisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a virtual channel platform of theinstant disclosure;

FIG. 1A is a cross-sectional view of the virtual channel platform of theinstant disclosure taken along line A-A in FIG. 1;

FIG. 1B is a cross-sectional view of the virtual channel platform of theinstant disclosure taken along line B-B in FIG. 1;

FIG. 1C is a cross-sectional view of an embodiment of the virtualchannel platform of the instant disclosure taken along line A-A in FIG.1;

FIG. 1D is a cross-sectional view of the embodiment of the virtualchannel platform of the instant disclosure taken along line B-B in FIG.1;

FIG. 2A is a schematic view of the virtual channel platform without themain driven fluid of the instant disclosure;

FIG. 2B is a schematic view of the virtual channel platform of theinstant disclosure in operation;

FIG. 2C is a schematic view of the virtual channel platform of theinstant disclosure in another operation state;

FIG. 3A is a schematic view of a main driven fluid filled in the virtualchannel that is in a tapered shape of the instant disclosure;

FIG. 3B is another schematic view of the main driven fluid filled in thevirtual channel that is in a meandered-shape of the instant disclosure;

FIG. 4A is a perspective view of a droplet channel platform of therelated art; and

FIG. 4B is a cross-sectional view of the droplet channel platform of therelated art taken along line C-C in FIG. 4A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIGS. 1, 1A, and 1B, which illustrate a virtual channelplatform 1 according to the instant disclosure, into which a main drivenfluid 2 is injected. When the virtual channel platform 1 generates anelectric field, the main driven fluid 2 located in the virtual channelplatform 1 moves in the virtual channel platform 1 under the influenceof the electric field. More specifically, the virtual channel platform 1includes two electrode plates 11, 12 and at least two spacers 13. When avoltage is applied to the two electrode plates 11, 12, the two electrodeplates 11, 12 will generate an electric field. The spacers 12 aredisposed between the two electrode plates 11, 12.

Specifically, the two electrode plates 11, 12 are a first electrodeplate 11 (hereafter referred as the upper electrode plate 11) and asecond electrode plate 12 (hereafter referred as the lower electrodeplate 12). Please refer to FIG. 1B, the upper electrode plate 11 furtherincludes a first substrate 111, a conductive layer 112 disposed on asurface of the first substrate 111 and a first hydrophobic layer 113disposed on a surface of the conductive layer 112. The first substrate111 may be made of glass, silicon, poly-dimethylsiloxane (PDMS),polyethylene terephthalate (PET), polyethylene naphthalate (PEN), aflexible polymer, and so on. The conductive layer 112 and the firsthydrophobic layer 113 can be manufactured by semiconductor manufacturingtechnologies, e.g. thin film manufacturing technology. Furthermore, theconductive layer 112 may be made of metal, e.g., copper-chromium, oxide,Indium Tin Oxide (ITO), or conductive polymers. The conductive layer 112can be deposited on the surface of the first substrate 111 by physicalvapor deposition including sputtering and evaporation. Furthermore, thematerial of the first hydrophobic layer 113 can be Teflon coated on thesurface of the conductive layer 112 by spin coating. Besides the spunTeflon, the first hydrophobic layer 113 may also be manufactured byother materials and other processes, including chemical or physicalvapor deposition, self-assembled formation of lipid surface monolayerand so on. It must be mentioned that the first hydrophobic layer 113 isoptionally disposed on the conductive layer 112 to facilitate handlingof the main driven fluid 2 and produces a hydrophobic surfacecharacteristic, thereby being convenient for driving the main drivenfluid 2. The formation of the virtual channel and fluid pumpingphenomenon may also occur on a virtual channel platform 1 without thefirst hydrophobic layer 113. Additionally, if the main driven fluid 2does not wet the surface of the conductive layer 112, the firsthydrophobic layer 113 may not necessary.

Further, it is worthy to mention that the material of the conductivelayer 112 is not limited to copper-chromium metal or Indium Tin Oxide,and it may be any one of conductive metal materials, conductive polymermaterials or conductive oxide materials.

In addition, Please refer to FIGS. 1C and 1D, the upper electrode plate11 further includes a first dielectric layer 114 disposed on a surfaceof the conductive layer 112. The first hydrophobic layer 113 is disposedon a surface of the dielectric layer 114. The material of the firstdielectric layer 114 may be parylene, a positive photoresist, a negativephotoresist or a material with a high dielectric constant, or a materialwith a low dielectric constant, and the above material may be coated onthe conductive layer 112 by spin coating, chemical or physical vapordeposition, sol-gel, or other thin film manufacturing technologies. Itis worthy to mention that first dielectric layer 114 is optionallydisposed on the upper electrode plate 11 according to the electriccharacteristic of the main driven fluid 2; that is, first dielectriclayer 114 may be disposed on the upper electrode plate 11; or firstdielectric layer 114 need not to be disposed on the upper electrodeplate 11 since the electric characteristic of the main driven fluid 2can meet the demands of the user.

The lower electrode plate 12 further includes a second substrate 121, apatterned conductive electrode 122 disposed on a surface of the secondsubstrate 121, a second dielectric layer 123 disposed on the patternedconductive electrode 122 and the second substrate 121, and a secondhydrophobic layer 124 disposed on a surface of the second dielectriclayer 123. The second substrate 121 may be a substrate plate made ofglass, silicon, poly-dimethylsiloxane (PDMS), polyethylene terephthalate(PET), polyethylene naphthalate (PEN), a flexible polymer, and so on.The patterned conductive electrode 122, the second dielectric layer 123,and the second hydrophobic layer 124 can be manufactured bysemiconductor manufacturing technologies.

Furthermore, the patterned conductive electrode 122 is not fixed inshape, which may be rectangle-shaped, strip-shaped, tapered,circular-shaped, meander-shaped, or formed in any other shapes. Theshape of the patterned conductive electrode 122 is determined based onuser's demands. Also, the patterned conductive electrode 122 may be madeof copper-chromium metal or Indium Tin Oxide (ITO), deposited byphysical vapor deposition, including sputtering and evaporation. Thematerial of the second dielectric layer 123 may be parylene, a positivephotoresist, a negative photoresist or a material with a high dielectricconstant, or a material with a low dielectric constant, and the abovematerial may be coated on the patterned conductive electrode 122 by spincoating, chemical or physical vapor deposition, sol-gel, or other thinfilm manufacturing technologies. It is worthy to mention that the seconddielectric layer 123 is optionally disposed on the lower electrode plate12 according to the electric characteristic of the main driven fluid 2;that is, the second dielectric layer 123 may be disposed on the lowerelectrode plate 12; or the second dielectric layer 123 need not to bedisposed on the lower electrode plate since the electric characteristicof the main driven fluid 2 can meet the demands of the user.Furthermore, the material of the second hydrophobic layer 124 is Teflon,and Teflon may also be coated on the surface of the conductive layer 112by spin coating. Besides spin coating of Teflon, the second hydrophobiclayer 124 may also be manufactured by other materials with otherprocesses, including chemical or physical vapor deposition,self-assembled monolayer, and so on.

It must be explained that the second hydrophobic layer 124 is optionallydisposed on the second dielectric layer 123 to facilitate liquidhandling of the main driven fluid 2. The formation of the virtualchannel and fluid pumping phenomenon may also occur on a virtual channelplatform 1 without the second hydrophobic layer 124. Additionally, ifthe main driven fluid 2 does not wet the surface of the seconddielectric layer 123, the second hydrophobic layer 124 may be notcoated. Furthermore, if the second dielectric layer 123 is not necessaryfor the electric characteristic of the main driven fluid 2 and the maindriven fluid 2 does not wet the surface of the conductive layer 122, thesecond hydrophobic layer 124 and the second dielectric layer 123 may benot coated.

Furthermore, the material of the patterned conductive electrode 122 isnot limited to copper-chromium metal or Indium Tin Oxide, and it may beany one of conductive metal materials, conductive polymer materials, orconductive oxide materials.

The at least two spacers 13 are disposed between the upper electrodeplate 11 and the lower electrode plate 12. The at least two spacers 13may be insulating gaskets so as to separate the upper electrode plate 11from the lower electrode plate 12 for forming a planar passageway 14into which the main driven fluid 2 is injected. A surrounding fluid 3 isalso injected into the planar passageway 14 for encompassing the maindriven fluid 2.

It is worthy to be mentioned that the surrounding fluid 3 is immisciblewith the main driven fluid 2. The main driven fluid 2 and thesurrounding fluid 3 are selected according to dielectric constants, aslong as the dielectric constant of the main driven fluid 2 is greaterthan that of the surrounding fluid 3. So the main driven fluid 2 may beaqueous solution (such as water) and the surrounding fluid 3 may be airor organic solution (such as silicone oil); alternatively, the maindriven fluid 2 may be organic solution (such as silicone oil) and thesurrounding fluid 3 may be air. More specifically, the main driven fluid2 and the surrounding fluid 3 are not limited to the above descriptions,that is, the fluid of the two fluids selected by users having a higherdielectric constant is the main driven fluid 2, and the other fluid ofthe two selected fluids is the surrounding fluid 3.

Please refer to FIGS. 1A, 2A, 2B, and 2C. A voltage source 4 iselectrically connected to the conductive layer 112 and the patternedconductive electrode 122, so that the conductive layer 112 and thepatterned conductive electrode 122 define a virtual reservoir 141 and avirtual channel 142 in communication with the virtual reservoir 141. Themain driven fluid 2 is arranged in the virtual reservoir 141. Said indetail, the patterned conductive electrode 122 has at least onestrip-shaped electrode and at least one rectangle-shaped electrode. Theconductive layer 112 and the at least one rectangle-shaped electrodedefine the virtual reservoir 141, and the conductive layer 112 and theat least one strip-shaped electrode define the virtual channel 142. Thelength (L) of the strip-shaped electrode of the patterned conductiveelectrode 122 divided by the width (W) of the strip-shaped electrode ofthe patterned conductive electrode 122 is greater than 5.0. The distance(D) between the first and the second electrode plates 11, 12 divided bythe width (W) of the patterned conductive electrode 122 is approximately(but not limited to) 0.5 to 2.0.

When the voltage source 4 supplies a voltage (V) between the conductivelayer 112 and the patterned conductive electrode 122, the electric fieldgenerates a force (such as the dielectrophoretic force, the DEP force)that drives the main driven fluid 2 from the virtual reservoir 141 tothe virtual channel 142. Thereby, the virtual channel 142 is filledfully with the main driven fluid 2. In addition, the DEP force isproportional to WV²/D.

That is to say, when voltage of different frequencies is applied to theconductive layer 112 of the upper electrode plate 11 and the conductiveelectrodes 122 of the lower electrode plate 12 to generate an electricfield, a force is generated between the interface of the main drivenfluid 2 and the surrounding fluid 3 by dielectrophoresis. The force actsat the interface from the high dielectric constant main driven fluid 2to the low dielectric constant surrounding fluid 3, so that the maindriven fluid 2 moves along the electric field towards the surroundingfluid 3.

In detail, under the influence of the electric field, the main drivenfluid 2 and the surrounding fluid 3 are electrically polarized indifferent degrees, so the molecules of the main driven fluid 2 and thesurrounding fluid 3 tend to be aligned in the direction of the electricfield. Further, if the electric field is spatially non-uniform generatedby the shape of the patterned conductive electrodes 122 of the lowerelectrode plate 12, the electrically polarized main driven fluid 2 andsurrounding fluid 3 under the influence of resultant (referred to as theDEP force) generate drift movements in different degrees, thereby themain driven fluid 2 can move in the virtual channel 142 of the planarpassageway 14 without a pump. Additionally, the main driven fluid 2 maymove in the virtual channel 142 of the planar passageway 14 in the formof liquid columns (as shown in FIG. 2C). Thus, the virtual channelplatform 1 of the instant disclosure can be used for guiding light viathe main driven fluid 2.

Furthermore, the patterned conductive electrode 122 may has a taperedelectrode, so that the virtual channel 142 can be tapered, and thevirtual channel 142 is full of the main driven fluid 2 (as shown in FIG.3A). Alternatively, the patterned conductive electrode 122 may has ameander-shaped electrode, so that the virtual channel 142 can bemeander-shaped, and the virtual channel 142 is full of the main drivenfluid 2 (as shown in FIG. 3B). In summary, the patterned conductiveelectrode 122 may has at least one of the strip-shaped electrode, therectangle-shaped electrode, the tapered electrode, and themeander-shaped electrode.

The operating frequency of the said voltage is greater than the cutofffrequency of the virtual channel platform 1. Specifically, the operatingfrequency of the voltage is approximately 8-12 times to the cutofffrequency of the virtual channel platform 1. For example, the cutofffrequency of such two parallel plates device (not shown) is 11.6 kHzwhen the distance between the parallel plates is 25 μm. However, theoperating frequency of the instant disclosure is 100 kHz when D is 25μm, which is sufficient to neglect the voltage drop across the seconddielectric layer 123 (if there is any) causingelectrowetting-on-dielectric (EWOD).

Consequently, the virtual channel platform of the instant disclosure hasthe beneficial effects as follows:

1. The virtual channel platform 1 of the instant disclosure has a simplestructure, has no movable component and can be programmably operated andcontrolled.

2. The virtual channel platform 1 of the instant disclosure may bemanufactured via a simple semiconductor process (lithography process)and applies the voltage of different frequencies to the two electrodeplates 11, 12 so as to generate an electric field in order to drive themain driven fluid 2, so that the main driven fluid 2 can move without asubstantial flow channel and an outer pump.

3. The virtual channel platform 1 of the instant disclosure does notneed a close substantial flow channel, and instead of using a movingcomponent (valve or pump) to drive the main driven fluid 2, the virtualchannel platform 1 flexibly controls and projects the conveying path ofthe main driven fluid 2 based on the electric field.

4. The virtual channel platform 1 of the instant disclosure can drivethe main driven fluid 2 to move in the way of liquid columns (continuousway).

5. The virtual channel platform 1 of the instant disclosure can savesample fluid and avoid waste.

What are disclosed above are only the specification and the drawings ofthe preferred embodiment of the instant disclosure and it is thereforenot intended that the instant disclosure be limited to the particularembodiment disclosed. It will be understood by those skilled in the artthat various equivalent changes may be made depending on thespecification and the drawings of the instant disclosure withoutdeparting from the scope of the instant disclosure.

1. A virtual channel platform, comprising: a first and a secondelectrode plates spaced for forming an electric field, the firstelectrode plate having a first substrate and a conductive layer disposedon the first substrate, the second electrode plate having a secondsubstrate and a patterned conductive electrode disposed on the secondsubstrate, wherein the conductive layer and the patterned conductiveelectrode define a virtual reservoir and a virtual channel incommunication with the virtual reservoir; a voltage source electricallyconnected to the conductive layer and the patterned conductiveelectrode; and a main driven fluid and a surrounding fluid arrangedbetween in the first and the second electrode plates, wherein thesurrounding fluid is immiscible with the main driven fluid, and the maindriven fluid is arranged in the virtual reservoir; wherein when thevoltage source provides a voltage between the conductive layer and thepatterned conductive electrode, the electric field generates a force indriving the main driven fluid from the virtual reservoir to the virtualchannel, allowing the virtual channel to be filled with the main drivenfluid fully.
 2. The virtual channel platform as claimed in claim 1,wherein the patterned conductive electrode has at least one of astrip-shaped electrode, a rectangle-shaped electrode, a taperedelectrode, and a meander-shaped electrode.
 3. The virtual channelplatform as claimed in claim 1, wherein the patterned conductiveelectrode has at least one strip-shaped electrode, and the conductivelayer and the at least one strip-shaped electrode define the virtualchannel.
 4. The virtual channel platform as claimed in claim 3, whereinthe length of the strip-shaped electrode divided by the width of thestrip-shaped electrode is greater than 5.0.
 5. The virtual channelplatform as claimed in claim 1, wherein the patterned conductiveelectrode has at least one rectangle-shaped electrode, and theconductive layer and the rectangle-shaped electrode define the virtualreservoir.
 6. The virtual channel platform as claimed in claim 1,wherein the operating frequency of the voltage is greater than thecutoff frequency of the virtual channel platform.
 7. The virtual channelplatform as claimed in claim 1, wherein a dielectric constant of themain driven fluid is greater than that of the surrounding fluid.
 8. Thevirtual channel platform as claimed in claim 1, wherein the main drivenfluid is an aqueous solution and the surrounding fluid is an air.
 9. Thevirtual channel platform as claimed in claim 1, wherein the main drivenfluid is an aqueous solution and the surrounding fluid is an organicsolution.
 10. The virtual channel platform as claimed in claim 1,wherein the main driven fluid is an organic solution and the surroundingfluid is an air.
 11. The virtual channel platform as claimed in claim 1,wherein the first electrode plate has a first hydrophobic layer coatedon the conductive layer.
 12. The virtual channel platform as claimed inclaim 11, wherein the second electrode plate has a second hydrophobiclayer.
 13. The virtual channel platform as claimed in claim 11, whereinthe second electrode plate has a second dielectric layer coated on thepatterned conductive electrode and the second substrate.
 14. The virtualchannel platform as claimed in claim 11, wherein the second electrodeplate has a second dielectric layer and a second hydrophobic layer,wherein the second dielectric layer is coated on the patternedconductive electrode and the second substrate, and the secondhydrophobic layer is coated on the second dielectric layer.
 15. Thevirtual channel platform as claimed in claim 1, wherein the firstelectrode plate has a first dielectric layer coated on the conductivelayer and a first hydrophobic layer coated on the first dielectriclayer.
 16. The virtual channel platform as claimed in claim 15, whereinthe second electrode plate has a second hydrophobic layer.
 17. Thevirtual channel platform as claimed in claim 15, wherein the secondelectrode plate has a second dielectric layer coated on the patternedconductive electrode and the second substrate.
 18. The virtual channelplatform as claimed in claim 15, wherein the second electrode plate hasa second dielectric layer and a second hydrophobic layer, wherein thesecond dielectric layer is coated on the patterned conductive electrodeand the second substrate, and the second hydrophobic layer is coated onthe second dielectric layer.
 19. The virtual channel platform as claimedin claim 1, wherein the first electrode plate has a first dielectriclayer coated on the conductive layer and the second electrode plate hasa second dielectric layer coated on the patterned conductive electrodeand the second substrate.